It is the overall objective of this proposal to study the psychopathology, course, and family of the Borderline Personality Disorder (BPD). While there is a great amount of literature on the BPD, empirical studies are few. The disorder is common in the general population as well as in treatment populations and utilizes many psychiatric resources. While the clinical literature has emphasized psychodynamics, etiology and treatment, there has been no systematic study of the BPD which makes both descriptive and psychodynamic assessments of psychopathology. The objective of the present proposal is two-fold, then. In the first part, a two year pilot study will devise and test measures, many of which are fully developed, to study the psychopathology and course of BPD subjects and to delineate the diagnoses of their first degree relatives. This pilot study will develop a research paradigm for the study of personality disorders in general, and the BPD in particular, using both descriptive and psychodynamic measures. It will also yield preliminary results comparing BPD subjects with Bipolar Type 2 manic Depressive and Antisocial Personality Disorder control subjects. The second part of the proposal involves a three year prospective study beginning at 18 months of the granting period employing the research paradigm on a larger sample which will cross-validate the initial findings. Following each subject for a period of 2 years, information will be gathered to delineate the interplay between life events, subject vulnerability to them, and subsequent measures of affective states, acting out, and behavioral regression. In addition, a family study will delineate the types and frequencies of psychiatric disorders in first degree relatives of subjects. The final result of this proposal would be a thorough test of the validity of the BPD. It should yield a comprehensive picture of its psychopathology, course and transmission relevant for both psychodynamically and descriptively oriented clinicians. Since the study will assess those aspects of the BPD which the literature suggests are most important, the implications for treatment will be salient and meaningful.